This invention relates to a leak-detecting check valve and a leak-detection alarm system. More particularly, the leak-detecting check valve has a function of detecting the movement of a valve element of said leak-detecting check valve when said check valve is attached to a water pipe or other conduit for water. In addition, the leak-detection alarm system includes said leak-detecting check valve and a signal-processing device that receives leak-detection signals from said leak-detecting check valve, analyzes said signals, and actuates an alarm that indicates that a leak has been detected.
A leaking water pipe in a building not only increases water costs needlessly, but also, depending on the location and degree of the leak, can cause damage to the building and property therein, and can cause various problems for inhabitants of the building. In particular, in a residential complex such as a condominium building or hotel, there is the danger that a single leak in an upper floor will cause great damage to many units and rooms on lower floors; there are quite a few cases of such damage. Therefore, in a residential complex, where damage can spread easily and where there is relatively little communication among residents, and in a hotel, where the lodgers usually are temporary and constantly changing, checking for water leaks should be done regularly. And if a leak is detected, it is necessary to promptly take responsive action, such as by alerting the manager and each resident or lodger, so as to prevent water damage from spreading.
There are two types of leaks that damage buildings and chattels. The first type is generally a small leak that occurs naturally because a decrepit water pipe suddenly breaks or develops a hole in it. The second type is a human-caused leak such as one that results because someone forgets to close a faucet, which causes a sink or tub to overflow, or is a leak that results because of a breakdown or operational error of equipment that uses tap water. In order to prevent a leak from causing damage, regardless of which type of leak it is, it must be detected soon after it occurs and it must actuate an alarm.
Some methods of full-time monitoring of a building to detect a leak therein have already been known. There is, for example, a method that measures acoustic vibrations transmitted through a water pipe and thereby detects leaks (See Patent Document 1). Another example is a method that detects a leak by using supersonic waves (see Patent Document 2). However, both of those methods require a large device, and if a leak is not a large one, they cannot detect it. Also, those methods cannot be used to detect human-caused leaks such as might result from forgetting to close a faucet.
Another example is a check valve that is capable of detecting the flow volume of a fluid through a pipe by measuring the magnetism of a magnet installed on said check valve by using a plurality of magnetism detectors installed on a valve casing that opposes said magnet—i.e., measuring the distance that a valve of said check valve moves in proportion to the rate of flow of the fluid that passes through said check valve (see Patent Document 3).
Another leak-detection method is one that detects pulsed signals by a sensor installed on a rotary flowmeter, collecting and analyzing the signals' data to determine if there is a leak (see Patent Document 4). One object of such an invention is to detect only naturally occurring (i.e., not directly caused by human action) minor leaks, and therefore such an invention determines the existence of a leak by comparing the flow of water when there is no leak in the water pipe with the flow of water when the water system is not in use. As such, it cannot respond to leaks caused by human actions.                [Patent Document 1] Unexamined Patent Publication 2002-122502 Gazette        [Patent Document 2] Unexamined Patent Publication 2002-131170 Gazette        [Patent Document 3] Unexamined Patent Publication 2000-205447 Gazette        [Patent Document 4] Unexamined Patent Publication 2002-055019 Gazette.        